1. Field of the Invention
This invention relates to processing visual recording data and, in particular, to evaluation of a set of visual recording data to identify whether the set of visual recording data includes one or more segments that do not correspond to recorded visual content.
2. Related Art
A set of visual recording data representing recorded visual content can include one or more segments that do not correspond to recorded visual content. For example, a break between two segments of recorded visual content (e.g., a break between a visual recording of a first scene or event and a visual recording of a second scene or event) can be delineated by a segment of visual recording data representing a constant color (e.g., blue, silver, black) or static (“snow”).
It is sometimes desirable to identify segments of a set of visual recording data that do not correspond to recorded visual content. For example, a videotape often includes recorded visual content only up to a certain point on the videotape; an end section of the videotape (which can be quite long and, in some cases, may comprise most of the videotape) is a blank section that does not include any recorded visual content. When converting the analog visual recording data stored on a videotape including a blank section at the end of the videotape to digital visual recording data to be stored on a digital data storage device, such as a DVD or CD-ROM, either the entire videotape must be processed or a determination must be made regarding when the blank section begins so that processing of the videotape can be terminated at that point. Processing the entire videotape is disadvantageous. This is because the apparatus used to process the videotape is occupied for longer than necessary (which can reduce the capacity of that apparatus to be used for other processing). This is also because the set of digital visual recording data produced by processing the videotape is larger than necessary (due to the data corresponding to the blank section), which can require more or larger digital data storage device(s) than are necessary (for example, when transferring video footage from a videotape to one or more DVDs or CD-ROMs, “blank” footage at the end of the videotape may require extra disks to be created that contain only footage without a true video signal). Therefore, it is desirable to identify when the blank section begins so that visual recording data after that point need not be processed.
It can also be desirable to identify segments of a set of visual recording data that do not correspond to recorded visual content in other situations and for other purposes. For example, it can be desirable to identify such segments to facilitate editing of a set of visual recording data. It can also be desirable to identify such segments to enable the segments to be eliminated so that the visual recording data requires less data storage capacity and/or so that a display of the visual recording data does not include a display of those segments.